<I am not quite sure I was able to understand, sorry. Are you saying that the bind-address value in /etc/mysql/my.cnf is set to 127.0.0.1 after enabling "Allow local MariaDB/MySQL server to accept external connections"?>
Thank you for your feedback. Yes, seems so. And so, the command "telnet MY_IP_ADDRESS 3306" does no work, not TCP packet answser from telnet. (While in the GUI is "Accept remote connections" configured, see screenshots on my other answers here)
And restart does also change nothing...
There is something 100% wrong